In general, a hybrid vehicle (HEV) includes an Engine Control Unit (ECU) for controlling an engine, a Motor Control Unit (MCU) for controlling the operation of a motor, a Transmission Control Unit (TCU) for controlling the operation of a transmission, a Battery Management System (BMS) for monitoring and managing battery status, and a Hybrid vehicle Control Unit (HCU) for controlling the operation of the above-described controllers, setting a hybrid operation mode and the overall operation of a vehicle.
For the HCU to control the operation of the controllers, a Controller Area Network (CAN) communication line and a separate hard wire for limp-home mode control must be provided. In the case where a CAN communication line on a BMS side is disconnected, the HCU cannot be aware of the state of a battery and, thus, the HCU excessively charges the battery that operates a motor, which may cause harm to the system. Due to this phenomenon, a vehicle shock may occur, which may, in a serious case, result in damage to an engine. Therefore, a problem arises in that critical harm is caused to the vehicle by the disconnection of a single CAN communication line.